Predictive Optical Calibration Scheduling for Excimer Light Sources
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Solution Overview
Problem
Existing calibration systems for optical devices in light sources, such as excimer lasers, perform calibrations based on pre-set usage values, leading to unnecessary downtime or failure to calibrate when necessary, affecting the accuracy of light beam measurements in photolithography processes.
Innovation Solution
A predictive calibration system that includes a prediction controller to analyze past performance data and schedule calibrations based on degradation metrics, adjusting operating parameters to maintain measurement accuracy without unnecessary downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calibration is performed based on pre-set usage values, then calibration reliability is improved, but productivity deteriorates due to unnecessary downtime
Solution Approach 1:
The system transitions from fixed pre-set usage values to dynamic degradation metrics that continuously change based on actual device performance. The degradation metric is calculated from multiple parameters including spectral feature measurements, error measurements, and usage data, allowing calibration scheduling to adapt to real-time device state rather than following a rigid schedule
Solution Approach 2:
The system implements continuous feedback by monitoring the optical device during operation, measuring spectral features, calculating degradation metrics, and using this information to dynamically adjust calibration scheduling. This closed-loop feedback mechanism ensures calibration is performed based on actual device condition rather than predetermined intervals
2Measurement precision
If calibration is performed more frequently, then measurement precision is improved, but loss of time increases due to unnecessary calibrations
Solution Approach 1:
The calibration schedule transitions from static pre-set intervals to dynamic scheduling based on real-time degradation metrics. The system continuously adjusts calibration timing according to the calculated degradation level, performing calibration only when the metric indicates it is necessary to maintain measurement precision
Solution Approach 2:
The system performs preliminary assessment by continuously calculating degradation metrics before calibration is needed. This allows the system to predict when calibration will be necessary and prepare accordingly, avoiding both premature and delayed calibration actions
Data Source
AI summary
A method is performed for scheduling a calibration relating to an optical device in a light source. The method can be performed by a calibration system including a calibration apparatus and a prediction controller. The method includes: receiving a property associated with the optical device while the optical device is being calibrated; calculating a current degradation metric based at least on the optical device property, the degradation metric modeling behavior of the optical device; estimating when a degradation of the optical device would exceed a threshold based on the current degradation metric; and scheduling a calibration of the optical device based at least in part on the estimate of optical device degradation.